1. Field
The present application relates to an image processing device and a recording medium that stores an image processing program that processes a color image.
2. Description of the Related Art
In order to accurately diagnose various diseases of animals including humans, diagnoses of pathological tissues and cells are indispensable. Among others, information about kinds, numbers and shapes of cells included in blood and bone marrow is indispensable in many diagnoses of diseases, and therefore, cells are collected from blood and bone marrow and specimens are obtained and then a technical expert observes differences in shapes and color tones of the cells using a microscope and judges the kinds and anomalies of individual cells. Such tasks (in which a technical expert directly looks into a microscope and makes a judgment manually based on his/her own experience) are carried out routinely in an inspection room of hospitals all over the world.
For example, the measurement of the number of eosinophils in blood gives critical information for diagnoses of allergic diseases. The number of eosinophils has increased in blood of patients of pollinosis and asthma. For the diagnoses, blood is collected from a patient and the blood is smeared and fixed onto a slide glass, and then a technical expert observes the Giemsa-stained specimen by using a microscope with a magnification of 1,000 (liquid immersion). Then, the technical expert diagnoses based on the existence of eosinophilics (reference: “Kensa To Gijutsu (Inspection and Technique)”, extra number, vol. 28, No. 7, 2000, IGAKU-SHOIN Ltd., “Standard Kensa ketsueki-Gaku (Standard Laboratory Hematology)”, compiled by The Japanese Society for Laboratory Hematology, Ishiyaku Publishers, Inc., 2003, 1st edition).
On the other hand, thanks to the recent development of digital technologies, each element of a microscopic image is converted into digital information and it is made possible not only to directly project an image on a screen but also to process the image in a variety of ways using software. If the task of judgment based on the experience of a technical expert is generalized into a method by which any one can make a distinction, it is made possible to considerably reduce the time and costs for the task.
In such circumstances, a color image of a stained specimen is taken in and pathological diagnoses of the specimen are made based on the image. It is normal to identify the kinds of individual cells based on the differences in forms of specimen images that appear in the image (for example, refer to non-patent document 1: Clinical & Laboratory Haematology, 2003, vol. 25, pp. 139-147, “Differential counting of blood leukocytes using automated microscopy and a decision support system based on artificial neural networks—evaluation of DiffMaster Octavia”). Instead of the diagnosis based on the differences in forms of specimen images, it is also proposed to identify the kinds of individual cells by plotting the values of each pixel of a color image of specimen in a predetermined color space and distinguishing the color differences for each kind of cell based on the sub-volume occupied by the values of each pixel in the color space (for example, refer to patent document 1: Japanese Unexamined Patent Application Publication No. 2003-506796).
The method, in which color difference for each kind of cells is distinguished based on the sub-volume in the color space, is however an indirect method. Recently, it is desired to directly distinguish the color difference for each kind of cells in a color image (real image) of specimen and make a diagnosis based on the color difference. However, the color difference for each kind of cells in a real image is extremely small and it is not possible to explicitly distinguish the color difference on the real image.